A Dictionary of Trails for Hikers 

access trail: Any trail that connects the main trail to a town, road, or another trail system.

backcountry trail : A primitive trail (can be open to motorized or nonmotorized users) in an area where there are no maintained roads or permanent buildings.

connecting or side trail: Provides additional points of access to major trails—in particular the nation’s national recreation, scenic, or historic trails per the National Trails System Act.